The freshwater reservoir effect is a potential problem when radiocarbon dating fish bones, shells, human bones, or food crusts on pottery from sites near rivers or lakes. The reservoir age in hardwater rivers can be up to several thousand years and may be highly variable. Accurate 14C dating of freshwater-based samples requires knowing the order of magnitude of the reservoir effect and its degree of variability. Measurements on modern riverine materials may not give a single reservoir age correction that can be applied to archaeological samples, but they show the order of magnitude and variability that can also be expected for the past. This knowledge will be applied to the dating of food crusts on pottery from the Mesolithic sites Kayhude at the Alster River and Schlamersdorf at the Trave River, both in Schleswig-Holstein, northern Germany.

Recently, several case studies have demonstrated the presence of human radiocarbon dietary reservoir effects in inland contexts. Freshwater reservoir effects present a high degree of variability, making it difficult to define local reservoir effect reference values necessary for correcting chronologies based on 14C dating of human bone material. Here, we investigate the hypothesis that 14C ages of edible freshwater species are delimited by the 14C ages of the main water carbon pools (DIC, POC, and DOC).

Water, plant, algae, bivalve, and fish samples were collected from lakes Schwerin and Ostorf (Germany). 14C and isotopic measurements were performed on the floral and faunal species and on water DIC, POC, and DOC. The results demonstrate the potential of the study area for large and variable freshwater reservoir effects. In the case of Lake Schwerin, the working hypothesis was verified as the 14C ages of faunal and floral species were delimited by the 14C ages of water DIC and POC, probably associated with 2 extreme categories of food chains (grazing and detritus). While the results obtained confirm the working hypothesis and suggest a relatively straightforward interpretation, further research is necessary to investigate possible spatial and seasonal variations.

The IntCal09 and Marine09 radiocarbon calibration curves have been revised utilizing newly available and updated data sets from 14C measurements on tree rings, plant macrofossils, speleothems, corals, and foraminifera. The calibration curves were derived from the data using the random walk model (RWM) used to generate IntCal09 and Marine09, which has been revised to account for additional uncertainties and error structures. The new curves were ratified at the 21st International Radiocarbon conference in July 2012 and are available as Supplemental Material at www.radiocarbon.org. The database can be accessed at http://intcal.qub.ac.uk/intcal13/.

In this paper, we report 11 AMS radiocarbon dates from 8 Prehispanic fortifications located in the Huaura Valley, central coast of Perú. Small fragments of organic material embedded in preserved mud mortar in architecture, and samples from construction layers exposed by looter's holes were used to date architectural features without undertaking extensive excavations. These dates contribute toward refining the chronology of fort building in the valley, and provide a test for assumptions about temporal change and architectural style. The results indicate that fortifications date to at least 3 periods. These data provide a starting point for exploring the occurrence of warfare through time on a regional scale.

The Ansanto Valley (southern Italy) is characterized by vents and boiling mud lakes that emit typical volcanic exhalations (mostly fossil CO2). This fossil dilution spreads over the Ansanto Valley and its impact on local trees is investigated in this study. Six trees at increasing distance from the emitting sources and 2 aliquots of gas were sampled. Dendrochronological analysis was performed on tree cores in order to check the accuracy of the tree-ring sequences; the results indicate no anomalies in the curves of the analyzed trees. δ13C and radiocarbon (14C) analyses were performed on the α-cellulose extracted from some selected tree rings. The main aim of δ13C analysis was to gain information about the origin of CO2 arising from the source; the results support the hypothesis of a carbonatic origin, with respect to a volcanic origin. 14C analysis was performed to evaluate the influence and to quantify the percentage of fossil dilution characterizing the local atmosphere and affecting the trees at different distances from the source during the years. The results show the presence of a strong fossil dilution affecting the trees, increasing toward the sources (from ∼6% at 80 m distance to ∼30% at 20 m from the nearest vent) with quite stable values over the examined period.

The first results of an optical method for measuring radiocarbon concentrations, based on mid-infrared laser spectroscopy of a carbon dioxide gas sample, are presented with the theoretical bases explained in detail. The first measurements on modern and highly enriched samples show the extreme linearity of this technique over more than 5 decades. An intercomparison with accelerator mass spectrometry (AMS) is performed both for modern and 14C-dead samples, assessing the almost perfect agreement of their respectively measured concentration values. The main features of our technique are compared with liquid scintillation counting (LSC) and AMS, and future developments of the current setup are discussed.

Research concerning the variability of the marine radiocarbon reservoir effect (ΔR) in the southern Iberian Atlantic coast confirms the existence of different ΔR values for regions that correspond to different oceanographic conditions. Due to these oceanographic conditions, the southern Iberian Atlantic coast can be divided into 3 zones: the Barlavento (windward), where the coastal waters are influenced by an intense upwelling of the northeastern Atlantic circulation (positive ΔR values); the Sotavento (leeward), where an upwelling area of minor intensity occurs; and the Andalusian coast, where because of its configuration does not present any wind-driven coastal upwelling (negative ΔR values). For the first time, ΔR values were determined for the Sotavento coastal region and, at the same time, new ΔR values were calculated for the Barlavento and the Andalusian coast for the last 3000 yr taking into account the data already obtained but now using a new methodology for calculation. In this way, ΔR weighted mean values were determined for the 3 regions of the southern Iberian Atlantic coast: ΔR = +69 ± 17 14C yr (Barlavento), ΔR = −26 ± 14 14C yr (Sotavento), and ΔR = −108 ± 31 14C yr (Andalusian coast). These values are in accordance with the different oceanographic conditions prevailing in these coastal regions. The data also allow identification of a Bond event at 0.8 ka cal BP and a drastic change in the oceanographic conditions in the Barlavento and Andalusian coastal areas during the 5th millennium cal BP.

The Southern Hemisphere SHCal04 radiocarbon calibration curve has been updated with the addition of new data sets extending measurements to 2145 cal BP and including the ANSTO Younger Dryas Huon pine data set. Outside the range of measured data, the curve is based upon the ern Hemisphere data sets as presented in IntCal13, with an interhemispheric offset averaging 43 ± 23 yr modeled by an autoregressive process to represent the short-term correlations in the offset.

The so-called Middle Settlement (Mellembygden) of Norse/Viking Greenland has received far less attention than either of its larger Eastern and Western counterparts. The Greenlandic Norse occupation is nominally taken to date between AD 985 and about AD 1450 and it is generally assumed that the Western Settlement was abandoned prior to the Eastern, but where the Middle Settlement fits into the pattern temporally has hitherto been completely unknown. This paper presents the first absolute dating evidence from the Middle Settlement. In addition to providing the results (14C, δ13C, δ15N) of a radiocarbon dating and stable isotope measurement program from domesticated (Bos, Ovis/Capra) and wild (Rangifer) animal bone and cultural-environmental (coastal, possibly midden) samples, the paper also addresses some problems of 14C estimation for the period of Norse occupation in Greenland. Investigations show a Medieval Scandinavian presence close to the start of the conventional landnám period (after AD 985) and with occupation continuing up to at least the 14th century AD. The start of this activity, found at 2 sites, bears comparison with various locations in both the Eastern and Western Settlement areas. The terminal phase of activity in the Middle Settlement is represented at 1 site only, but despite this limitation, it shows that the Norse may have been present for most of the period that they occupied sites in both the Western and Eastern settlements. Caribou bone from separate contexts that also contained Thule Inuit material proves useful in indicating dates for a probable post-Norse Inuit presence. The position of age estimates on the calibration curve underscores the need to look critically at such evidence when making chronological inference during the Norse period owing to the existence of plateaus and wiggles. The inclusion of samples from both domesticated and wild fauna considered to be possibly modern, yet reported from archaeological assemblages, provides a warning to archaeozoologists to be especially vigilant when considering the potential non-contemporaneity of material.

High radiocarbon sample throughput is an increasingly important requirement of accelerator mass spectrometry (AMS) systems, which in turn requires high source output. To accomplish this, HVE AMS systems use a model SO-110B ion source, which can run at outputs of more than 200 μA 12C. It is known that high source output may compromise precision. To quantify this effect, we have tested an HVE 1MV AMS system for the influence of medium (100 μA) and high (200 μA) source outputs on the precision. These early measurements indicate for a 200 μA 12C source output, equivalent to a ≃1 kHz 14C count rate for Ox II samples, a 13C/12C precision of 1% and a 14C/12C precision of 3% can be obtained.

We report results of duplicate measurements of dissolved organic carbon concentrations ([DOC] as μM) and Δ14C in seawater in order to assess the total uncertainty of reported [DOC] and Δ14C measurements via the UV oxidation method. In addition, pure International Atomic Energy Agency standards analyzed over a 4-yr period are evaluated. We find the total uncertainty of Δ14C measurements to be ±4.0. However, in samples that were thawed, subsampled, and refrozen prior to UV oxidation, the total uncertainty of Δ14C measurements is on the order of ±10. The [DOC] measurements of these samples were also higher by 1.8 ± 0.3 μM. The reason(s) for these documented increases in total [DOC] and Δ14C uncertainty are unclear. In order to minimize any effects on sample measurements, we recommend the following: 1) regular monitoring of duplicate samples, DOC standards, and diluent (Milli-Q™) water for Δ14C and [DOC] measurements; 2) thawing a sample immediately and only once prior to UV oxidation; 3) avoid the use of DOC-leachable plumbing (such as PVC pipe) in both water systems feeding and within Milli-Q systems; and 4) consider the use of DOC-free diluents (i.e. pre-UV oxidized Milli-Q or sample water).

A simple way to upgrade the Peking University 500kV NEC radiocarbon facility (CAMS) for 10Be measurements is presented. In a first phase, a silicon nitride foil as passive boron degrader was mounted in front of the electrostatic deflector near the focal plane of 10Be. The Si detector at the end of the beam line was replaced with a high-resolution ΔE-Eres gas ionization chamber. In addition, a Faraday cup for the measurement of 9Be1+ was installed. Tests with this arrangement showed promising results: a 10Be/9Be background level of 3.4 × 10–14 and an overall transmission for 10Be of 2.2% were obtained. Measurements of standards showed very good stability and reproducibility. In the next step, it is planned to add a second magnet to reduce the background and to partly compensate losses due to energy and angular straggling in the degrader foil by the energy and angular refocusing effect of a magnetic sector field. With this final arrangement, a performance with 10Be/9Be background levels at 10−15 and 10Be overall transmission of 6–7% can be expected. The design proposed in this paper has the advantage that the modifications can be realized in a rather inexpensive way and that the measurement performance for 14C will not be affected.

Recent fieldwork by the Industries of Angkor Project (INDAP) has identified the first extensive evidence of iron production within an Angkorian Khmer (9th to 15th centuries AD) center at Preah Khan of Kompong Svay (Preah Khan) in Preah Vihear province, Cambodia. This immense 22-km2 temple complex appears to be an outpost of Khmer settlement situated in close proximity to Phnom Dek (“Iron Mountain”), the richest known source of iron oxide in Cambodia. Combined with the fact that Preah Khan's temple architecture dates between the late 10th to early 13th centuries, the period that the Khmer greatly expanded their territorial influence, our primary hypothesis is that this complex was established to gain access to and monitor production of iron for the capital of Angkor. The vast number and size of these iron slag concentrations, some up to 5 m in height by 35 m in length, precludes the use of traditional excavation and dating methods. Instead, this paper employs 14C dating of “in-slag” charcoal from surface slag cakes to produce a spatial chronology of late or “terminal” industrial activities. The results indicate that metallurgy was “last” practiced at various locations within Preah Khan in the mid-13th to late 17th centuries, with 3 distinct clusters between the late 13th and late 15th centuries. Based on this initial survey of surface collections, it appears that iron production at Preah Khan occurred after the final phase of masonry construction. More significantly, this work provides the first robust set of dates for late Angkorian and Middle period industrial activities in Cambodia.

This article outlines the Bayesian models and methods used to facilitate construction of the 2013 internationally agreed radiocarbon calibration curves known as IntCal13, Marine13, and SHCal13. The models build on those used for the 2004 and 2009 estimates of the curves and, as in 2009, arc implemented using Markov chain Monte Carlo sampling, specifically a Metropolis-within-Gibbs sampler. In addition to the data structures accounted for within the 2004 and 2009 models, the approach outlined here also allows for: the presence of additional uncertainty that the data providers have been unable to quantify; tree-ring data that derive their calendar age from wiggle-matching (in addition to ring counting); varve-counted data that exhibit zero increase in calendar age error between 2 or more consecutive layers; and any data source for which we have dependent calendar age uncertainties.